Prime-mover-control system



Oct. 14, 1930. c. w. PLACE 1,773,644

PRIME MOVER CONTROL SYSTEM Original Filed Dec. 29, 1927 Inventor; ClaudePlace,

His Attorney.

Patented Oct. 14, 1930 UNITED STATES GLAUDE w. YLACE, OF LA GRANGE,ILLINOIS, ASSIG-NOR 'I'O GEN ERA-l1 ELEG'IEEG PA'NY, A. CORPORATION OFNEW YORK PRIME-MOVEB-GONTROL SYSTEM Oricinal application filed December29, 1927, Serial No. 243,418. Divided and this application filed Eifiarc80, 1929. Serial No. 351,274.

This application is a division of my applicatipn, Serial N 0. 243,418,filed December 29, 192

This invention relates to prime mover control systems and particularlyto systems for automatically starting prime movers which drivedynamo-electric machines and one of its objects isto provide an improvedarrangement for preventing a' prime mover from accelerating to anabnormal speed during the starting operation thereof.

Certain types of prime movers require a relatively large gate opening tostart them from rest and if this gate opening is maintained after theprime movers start they will accelerate to and above their normal speedvery rapidly so that when these prime movers are not provided with adirect connected governor the prime mover may accelerate to a very highspeed during the starting operation. In accordance with my invention 1provide an arrangement for effecting a decrease in the gate opening assoon as the prime mover starts.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing which showsdiagrammaticlly a control sys tem for a prime mover dynamo-electricplant embodying my invention, and its scope will be pointed out in theappended claims.

Referring to the drawing 1 represents a prime mover dynamo-electricplant comprising a water wheel 2 driving a generator 3 and an exciter l.The supply of fluid energy to the water wheel 2 may be controlled by anysuitable means such as a ate 7 which in turn is controlled b any suitale governing means 8 examples of which are well known in the art.

As shown in the drawing the governing means comprises a motor driven flyball governor having a movable member 10 which is arranged in anysuitable manner, examples of which are well known in the art so that theposition thereof determines the opening of the gate. As diagrammaticallyshown in the drawing the member 10 is in the gate closed position and isheld in that position by a closing spring 11 against the bias of anoperating spring 12 as long as a magnet 13 is deenergized. Whenever itis desired to place the prime mover l in operation it is necessary toenergize the magnet 13 which is so arranged that its energization movesthe closing spring 11 out-of operative relation with the member 10 andallows the spring 12 to move the member to a gate opening position. Aslong as the magnet 13 is energized the gate opening position of themember 10 depends upon the position of the fly balls 15 which may bedriven at a speed proportional to the speed of prime mover by anysuitable means such as an electric motor 10 which is normally arrangedto be energized by the generator 3.

The generator 3 is arranged to be connected to a load circuit 18 bysuitable switching means 19 and the exciter l is arranged to beconnected to the generator field winding by suitable switching means 20.The operation of the switching means 19 and 20 may be effected in anysuitable manner either automatically or manually, examples of which arewell known in the art. As shown in the drawing switching means 19 ismanually controlled and the switching means 20 is arranged to be closedby a winding 21, which is responsive to the exciter voltage, when theexciter voltage is above a predetermined value.

The initial energirzation of magnet 13 to start the plant may be efiected in any suit able manner, examples of which are well known in theart. As shown in the drawing the circuit of the magnet 13, when theplant is shut down, is arranged to be completed by a switch 23. In orderto efiect a decrease in the gate opening as soon as the plant starts Iprovide a speed switch 2 1 which is responsive to the speed of the primemover and which is arranged to efiect the opening of the originalstarting circuit of the magnet 13 as soon as the prime mover speedreaches a predetermined snhnormal value.

It will be noted that due to the slow r te at which the eXclt-er andgenerator voltages may build up the motor 16, if it were permanentlyconnected to the generator, probably would not be up to its normal speedto limit the gate opening to its proper value, by the time the rimemover would reach its normal s eed urin the starting thereof.

In order t at the fly lialls 15 may be rotating at substantially normalspeed and thereby be operative to limit the position of the member 10 toits normal operating position by the time the prime mover hasaccelerated to its normal speed, I provide an arrangement whereby duringthe starting operation the motor 16 is first connected to an auxiliaryenergized source of current 25 and then when the generator is'in anoperative condition to supply current to the motor it is transferredfrom the auxiliary source 25 to the generator 3. For connecting themotor 16 to the auxiliary source 25 I provide a switch 27 which isarranged to be closed in any suitable manner when the speed of the primemover is above a predetermined subnormal value. As shown the switch 27is provided with a closing coil 28 the circuit of which is arranged tobe completed in response to the closing of the contacts 36 of the speedresponsive means 24. I also provide a switching device 29 which isarranged to be operated to disconnect the motor 16 from the source 25and to connect the motor 16 to the generator 3 when the generator is inan operative condition to supply current to the motor 16. Any suitablemeans, examples of which are well known in the art, which is responsiveto a predetermined condition of the generator indicating the operativecondition thereof such as the speed, voltage, frequenc etc., may beemployed tocontrol the se ective operation of the switching means 29. Asshown in the drawing the switching means 29 is provided with anoperating coil 30 which is arranged to be connected across the generator3 when the switch 20 is closed and which is designed to operate theswitching means 29 so as to connect the motor to the generator 3 onlywhen the generator voltage is above a predetermined value. Since thegenerator voltage depends upon the excitation and speed of the generatorit is evident that the o eration of the switching means also depen 5upon both the excitatlon and speed of the generator. Preferably thenecessary generator voltage to operate the switch 29 can be obtamed onlwhen the generator is operating at a hig er speed than the speed atwhich the speed responsive device 24 closes its contacts. In order toreenergize the governor magnet 13 after its circuit has been opened bythe operation of the speed responsive device 24 and the motor 16 hassubsequently reached its normal speed so that the fly balls areoperative to control the governor I provide a relay 33 which isresponsive to the voltage across the terminals of the fly ball motor 16and which is arranged when energized a predetermined amount to completea circuit for the magnet 13. If desirable the relay 33 may be designedin any suitable manner so that it does not operate to reenergize themagnet 13 until a predetermined time after the voltage impressed on therela 33 is above a predetermined value. Suc an arrangement may bedesirable in order to insure a predetermined closing of the gate afterthe prime mover starts.

The operation of the system shown in the drawing is as follows:

When it is desired to start the prime mover plant the switch 23 isclosed so that the magnet 13 is energized through contacts 34 on switch27 to move the closing spring 11 out of operative relation with themember 10 and to permit the operating spring 12 to move the member 10 toa gate opening position. If desirable, the opening movement of themember 10 may be retarded in any suitable manner such as a dash pot 35.The governor 8 continues, to open the gate 7 ,until the waterwheel 2starts and the speed thereof reaches a value suificient to cause speedresponsive means 24 to close its contacts 36. A circuit is thencompleted for the.closing coil 28 of switch 27 so that the fly ballmotor 16 is connected across the auxiliary energized source 25 and theoriginal energizing circuit of the magnet 13 is opened at auxiliarycontacts 34. The closing spring 11 then causes the member 10 to movetowards thev gate closing position so that the gate 7 in turn is movedtowards its closed position to decrease the supply of waterto the waterwheel. As soon as the switch 27 closes, the motor 16 starts to rotateand comes up to its normal speed very quickly. Preferably the fre quencyof the source 25 is substantially the same as the normal frequency ofthe generators 3 so that the fly balls 15 when the motor 16 is connectedto the auxiliary source maintains the speed of the water wheel atsubstantially the same value it does during normal operating conditionswhen it is c011- nected to the generator. When the voltage across theterminals of the motor 16 builds up to a predetermined value, relay 33becomes operative to close its contacts 38 and thereby reenergize themagnet 13.

As the water wheel accelerates the voltage of the exciter 4 builds upand when it reaches a predetermined value switch 20 closes its contacts40 and 41. The closing of the contacts 40 connects the generator fieldacross the terminals of the exciter 4 and the closing of the contacts 41connects the closing coil 30 of the switching means 29 across thegenerator terminals so that when the generator voltage is aboveapredetermined value the switching means 29 is operated to disconnectthe fly ball motor 16 from the auxiliary source 25 and to connect themotor 16 across the generator terminals. The fly balls .15 are thendriven at a speed dependent upon the frequency of the enerator 3 so thatthe position of the ate% is controlled to maintain the speed 0 thewaterwheel at a predetermined value.

It will be noted that if the exciter fails or any other abnormalcondition occurs so that either the winding 21 or the winding becomesdeenergized while the plant is in operation, the switch 29 o erates toreconnect the motor 16 to the auxiliary source 25 so as to prevent theprime mover from running awayil 'le I have in accordance with the patentstatutes shown and described my invention as applied to a particularsystem and as embodying various devices diagrammatically indicated,changes and modifications will be obvious to those skilled in the art,and I therefore aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In combination, a prime mover, a gate for controlling the supply ofenergy to said prime mover, a fly ball governor for controlling saidgate comprising a magnet which when energized eflects the opening ofsaid gate and which when deenergized effects the closing of said gate,an electric motor for driving the fly balls of said governor, means forenergizing said magnet to eflect the starting of said prime mover, asource of current, means responsive to a predetermined speed of saidprime mover for effecting the connection of said motor to said sourceand the deenergization of said magnet, and means responsive to theenergization of said motor for effecting the subsequent energization ofsaid magnet.

2. In combination, a prime mover, a gate for controlling the supply ofenergy to said prime mover, a fly ball governor for controlling saidgate comprising a magnet which when energized elfects the opening of sad gate and which when deenergized effects the closing of said gate, anelectric motor for driving the fly balls of said governor, means forenergizing said magnet to eflect the starting of said prime mover, asource of current, means for connecting said motor to said source, meansresponsive to a predetermined subnormal speed of said prime mover foreffecting the deenergization of said magnet, and means operative inaccordance with a predetermined condition of said motor for reenergizingsaid magnet.

3. In combination, a prime mover, a gate for controlling the supply ofenergy to said prime mover, a fly ball governor for controlling saidgate comprising a magnet which when energized effects the opening ofsaid gate and which when deenergized eflects the closing of said gate,an electric motor for driving the fly balls of said governor, means forenergizing said magnet to effect the starting of said prime mover, asource of current, means responsive to a predetermined speed of saidprime mover for effecting the connection of said motor to said sourceand the deenergization of said magnet, and a relay responsive to thevoltage across the terminals of said motor for reenergizing said magnet.

L. In combination, a prime mover, a gate for controlling the supply ofenergy to said prime mover, a fly ball governor for controllingsaid gatecomprising a magnet which when energized effects the opening of saidgate and which when deenergized efiects the closing of said gate, anelectric motor for driving the fly balls of said governor, means forenergizing said magnet to effect the starting of said prime mover, asource of current, and means responsive to a redetermined speed of saidprime mover or connecting said motor to said source.

In witness whereof, I have hereunto set my hand this 27th day of March,1929.

CLAUDE W. PLACE.

